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38 lines
1.4 KiB
C
38 lines
1.4 KiB
C
#include "01_func.h" // See a few pages up for declarations
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#include <assert.h>
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#include <stdio.h>
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#include <stdlib.h>
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void a_function( int ( *func )( char * ), char prompt[] ) {
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( *func )( prompt ); // Call function with arguments
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}
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int main( int argc, char *argv[] ) {
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int x = 0;
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int *p = &x; // Get x's memory address
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printf( "%p\n", p ); // Print the address of x
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printf( "%d\n", *p ); // Dereference pointer (get contents of memory location)
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*p = 10; // Dereference assign
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int **dbl_p = &p; // Double pointer (pointer to pointer to value)
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int *null_p = NULL; // Create NULL pointer
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*null_p = 1; // Segmentation fault due to null pointer dereference
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// pointer arithmetic
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int arr[ 3 ] = { 2, 3, 4 };
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char c_arr[ 3 ] = { 'A', 'B', 'C' };
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int *arr_p = &arr[ 1 ];
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char *c_arr_p = &c_arr[ 1 ];
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c_arr_p += 1; // Now points to c_arr[2]
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arr_p -= 1; // Now points to arr[0]
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char *arr_p_c = (char *) arr_p; // Cast to char pointer (points to first byte of arr[0])
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printf( "%d", *( arr_p - 5 ) ); // No boundary checks (can access any memory)
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assert( arr == &( arr[ 0 ] ) ); // Evaluates to true
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int new_arr[ 3 ] = arr; // Compile time error (cannot use other array as initializer)
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int *new_arr_p = &arr[ 0 ]; // This works
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a_function( &get_user_input_int, c_arr );
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return EXIT_SUCCESS;
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}
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